A substantial amount of research and development effort has been directed towards the development and improvement of gas turbine parts and other similar aerospace components.
For certain applications, there exists a need for lightweight materials with good elevated temperature mechanical properties in combination with resistance to oxidation at elevated temperatures. Typical of these applications are compressor blades used in gas turbine engines.
Some of the best materials developed to date for such applications are titanium and the alloys based on titanium. However, the high reactivity of titanium with oxygen at elevated temperatures limits their use.
In "Ion Implantation," 729-738, Vol. 8 (1973) of a series of books published by North-Holland Publishing Company Ltd.--London, G. Dearnaley et al discuss corrosion studies in ion implanted metals. According to the authors, the metal ion species, arranged in order of their effectiveness in inhibiting the thermal oxidation of titanium at 600.degree. C. are as follows: calcium, europium, cerium, yttrium, zinc, aluminum, indium, nickel and bismuth. While implantation of the metal ions disclosed by the authors do apparently provide a degree of protection against oxidation of titanium, mere ion implantation with the particular metal ions disclosed is ineffective in plating titanium or titanium alloy components with an oxidation-resistant protective coating so as to provide improved mechanical properties in gas turbine compressor environments.
U.S. Pat. No. 4,137,370 by Fujishiro et al discloses a process for improving the fatigue properties of titanium alloy through the use of ion plating to provide a noble metal protective layer on the surface of the article.